comprehension parsing

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On 05/11/2022 22:11, MRAB wrote:
> On 2022-11-05 18:52, cactus wrote:
>> On Saturday, 5 November 2022 at 16:06:52 UTC, cactus wrote:
>>
>> I should have quoted the full comprehensions:
>>
>>   all((srt(m, n) in c_np) == (srt(a, b) in c_ap)  for (m, a), (n, b) 
>> in combinations(na8, 2))
>>   all( srt(m, n) in c_np  ==  srt(a, b) in c_ap)  for (m, a), (n, b) 
>> in combinations(na8, 2))
> 
> The comparison operators can be chained, so:
> 
>      a == b == c
> 
> is equivalent to:
> 
>      (a == b) and (b == c)
> 
> except that the common term ('b' in this case) is evaluated only once.
> 
> 'in' is one of those comparison operators, so:
> 
>       srt(m, n) in c_np == srt(a, b) in c_ap
> 
> is equivalent to:
> 
>       (srt(m, n) in c_np) and (c_np == srt(a, b)) and (srt(a, b) in c_ap)
> 
> except that the common terms ('c_np' and 'srt(a, b)') are evaluated only 
> once.
> 
> Chaining makes most sense with multiple '==' or a series of '<' and/or 
> '<=' or a series of '>' and/or '>=', as in '1 <= n <= 10'.

Thanks for a most helpful explanation